1. Field of the Invention
The present invention relates to a method for the arrangement of power supply with an expansion card as set forth in the appended claim 1, an expansion card as set forth in the appended claim 6, and a mobile station as set forth in the appended claim 10.
2. Prior Art
The PCMCIA connection (Personal Computer Memory Card International Association) is a known connection used with electronic devices for connecting expansion cards, such as memory cards (e.g. FLASH memory cards), modems and various input/output (I/O) cards with the electronic device. Thus, the electronic device and the PCMCIA card are provided with connectors complying with the PCMCIA standard so that the connector of the electronic device is a so-called male connector, i.e. it has connector pins, and the card connector is a so-called female connector, i.e. it has conductor sockets, wherein when the PCMCIA card is connected with the PCMCIA connection of the electronic device, an electric coupling is formed between each connector pin and the corresponding conductor socket. The PCMCIA standard defines the usual functions for each connector pin and corresponding conductor socket. Consequently, for example in an application where the PCMCIA connection is implemented in a computer, each data line in the data bus of the computer is connected to one connector pin in the PCMCIA connection. Further, at least some of the address and control lines are connected to the connector.
PCMCIA cards have the size of a credit card (85.6 mm.times.54 mm), but the thickness of the cards may be 3.3 mm (type I), 5.0 mm (type II) or 10.5 mm (type III). Electrically, the PCMCIA cards are connected with an electronic device as an 8/16 bit I/O connection or memory. The card complying with the PCMCIA standard has a memory area which is readable to the electronic device and contains information for identifying the card, i.e. an information structure data file (card information structure, CIS) which is also called a configuration means.
Particularly in connection with portable computers (Laptop PC), mobile station applications have been developed in which at least the transmitter/receiver unit of the mobile station Is arranged in the PCMCIA standard card form. The unit used for controlling the operation of the card is advantageously a microcontroller (MCU) comprising e.g. a processor, a memory (RAM, ROM), and I/O lines for connecting the microcontroller with the other electronics of the card. Further, an external memory can be connected to the microcontroller.
The transmitter comprises e.g. a modulator for modulating the signal to be transmitted, filters particularly for attenuating spurious emissions, a mixer where the modulated signal is mixed with the local oscillator frequency for generating a radio-frequency signal, and a power amplifier for amplifying the signal to be transmitted. The amplified signal is transmitted to an antenna which is coupled to the card e.g. via a cable. The receiver comprises e.g. filters for filtering received signals: a mixer for converting the received radio-frequency signal to an intermediate frequency or, in a direct conversion type receiver, to the baseband frequency: and a detector for demodulating the received signal.
When an expansion card according to e.g. the PCMCIA standard is connected to the PCMCIA expansion card connection of a computer, the operating voltages of the expansion card are switched on at the same time when the expansion card is inserted in its place.
Another known solution for the arrangement of the power supply to the expansion card is that the expansion card is provided with a switch whereby the power supply can be turned on and off when necessary. This solution requires that a switch is arranged in the expansion card, which increases the manufacturing costs of the expansion card, and further, the switch requires space on the expansion card. Another disadvantage in such an arrangement is that the power required by the expansion card upon turning on may rise to a great level. This will result in a momentary peak in the current intensity, which may induce current peaks in the power supply circuits of the computer, and the current intensity may momentarily exceed the maximum value allowed for the voltage supply pins of the connector.